Any rival who drains votes away from the rising Newt Gingrich — as Paul’s allies believe he does — could help keep Romney’s chief opponent at bay here. But Paul’s traditional, all-out campaign in Iowa has pushed the libertarian congressman into second in a key Iowa poll — and the reality is that even if he wins the caucuses, many Republicans say, he likely can’t win the Republican presidential nomination.

That means, Romney allies privately say, that Paul’s success may be Romney’s gain.

Part of it’s because Paul has a history of organizing to win straw polls around the country, but earns little attention or credibility as a mainstream candidate in return. He came within about 150 votes of beating Rep. Michele Bachmann at the key Iowa test vote in August — but his near-victory was barely covered, supporters complain.

That same yawn could also greet his performance in the caucuses. And even if he does get the recognition that past surprise caucus performers have found, Republicans say he’d have trouble moving on to challenge Romney in New Hampshire, South Carolina and Florida the way Gingrich could.